In the related art, as a device which performs angiography, for example, a fundus camera, a scanning laser optometry device, or the like has been known. In using this type of devices, a contrast agent which emits light with specific excitation light is injected into a body of a specimen. The device receives light from the contrast agent to obtain an angiographic image. That is, in the related art, the injection of the contrast agent is required.
In recent years, a device which obtains motion contrast by applying an optical coherence tomography (OCT) technique without using a contrast agent has been suggested as described in the following related-art documents.    Patent Document 1:
International Patent Publication No. 2010/143601    Non-Patent Document 1:
Yonghua Zhao et al. OPTICS LETTERS/Vol. 25, No. 2/Jan. 15, 2000    Non-Patent Document 2:
Adrian Mariampillai et al. OPTICS LETTERS/Vol. 33, No. 13/Jul. 1, 2008    Non-Patent Document 3
Vivek J. Srinivasan et al. OPTICS LETTERS/Vol. 35, No. 1/Jan. 1, 2010
However, it is considered that a technique for obtaining a functional OCT image, such as motion contrast, using OCT is still developing and stands further improvement.